Inviting Civic Party leader Audrey Eu Yuet-mee to a debate on the political reform package for 2012 was bound to be a risk for Chief Executive Donald Tsang Yam-kuen. Many people thought Tsang was crazy when he issued the invitation just days after the by-elections that pan-democrat lawmakers had forced by resigning.

Government supporters who criticised Eu and her colleagues for pulling the referendum stunt at public expense were angry to see her rewarded with a platform next to him on television. And many of Tsang's opponents - and supporters - wondered whether his debating skills could match Eu's.

I think Tsang extended the invitation to prove to the people of Hong Kong his seriousness in getting his reform package through the Legislative Council next Wednesday. He knew the risks.

How did it go? If we see the debate as a beauty contest, there is only one possible conclusion: Eu won. There was no way Tsang, a conservative former bureaucrat and ill at ease in a formal debate, could match Eu's style, with her constant eye-contact with the camera and expressive body language. While he listed facts, she appealed to people's emotions. (He made his points with more confidence at the press conference afterwards.)

But the chief executive did not hold the debate to try to win on points for the performance. For him, winning was about convincing the people that the reform package, for all its faults, deserves to go through as a step towards meaningful future change.

Did the debate improve the chances of the package being passed?

Probably not. It was easy for Eu to attack Tsang for not doing enough to fight for Hong Kong. In fact, she has no idea what he and his colleagues have been saying behind closed doors to Beijing officials. Some of his comments implied that his success in getting a timetable for universal suffrage took a lot of hard work. But he can't even hint openly that disagreement between Hong Kong and Beijing officials even exists. So Eu's accusation sounds convincing to many people.

At the same time, Tsang could not come up with an effective response to Eu's point that the functional constituencies work against the public interest. She mentioned catering representative Tommy Cheung Yu-yan's comments in March on the minimum wage, property developers' misleading flat sizes and the banking representative's role in the Lehman Brothers minibonds saga. Public opinion is on her side here.

Tsang's argument was that his package is a step towards solving the problem of small-circle functional constituencies. Again it was easy for Eu to score points here. Tsang has to find agreement among Beijing, the Hong Kong government and Legco to implement reform; Eu has the luxury of not having to bother - to her, it seems, things change at the snap of one's fingers.

Her position is less realistic than Tsang's, but it sounds better to the public.

Although the debate started off with both bickering over the opinion polls, it got exciting. Tsang in particular seemed to become more aggressive when the language switched to English. Towards the end, the gap between the two sides - and maybe the division between the two camps in our community - became very clear.

Why waste an opportunity and another five years? This is the ultimate argument that Tsang had, and it is one I sympathise with. The idea of rejecting the package strikes me as absurd; we need to get it out of the way so we can take the next step and hopefully give future Hong Kong governments the legitimacy they need to get things done.

But Eu rejected that argument out of hand. She said she couldn't sign up for something when she doesn't know what comes next. She spoke of looking after the next generation by not taking a half-step forward. It is a frustrating and emotional argument. I think Tsang spoke from the heart when he replied that the whole dispute over reform was harming the trust in the central and local governments.

By holding the debate with his No1 opponent, Tsang was making a sincere appeal to the community. But instant polls suggest the approach did not work. To people watching at home who had already made up their mind on the package, the debate would not have changed much. To viewers who had previously been undecided, Eu came out on top.

In Legco, which is where it really matters come Wednesday, being undecided just won't do.

Bernard Chan is a former member of the executive and legislative councils